Molecular Detection of blaIMP Genes in Metallo-Beta-Lactamase Producing Clinical Gram-Negative Isolates

The use of carbapenem antibiotics in the treatment of serious Gram-negative bacterial infections is under threat due to the emergence of the blaIMP gene amongst the bacterial pathogens.

The present descriptive cross-sectional study aimed to determine the occurrence of the blaIMP gene and minimum inhibitory concentrations (MICs) of the bacterial pathogens. The carbapenem-resistant isolates were screened out for the detection of MBLs by using the modified Hodge test and disk potentiation method. MBL producing strains were tested for the presence of the blaIMP gene by using PCR technique. The MICs of the blaIMP gene positive bacterial isolates were detected on the Vitek 2 system (bioMerieux).

The primary source of MBLs and blaIPM gene carrying bacterial pathogens was blood (38.5%). We isolated 104 bacterial isolates in the initial screening of carbapenem resistance. Metallo-beta-lactamases (MBLs) were detected in 76 (73%) of the isolates which predominantly included 27 (26%) Klebsiella pneumoniae, 20 (19.2%) Acinetobacter baumannii, 16 (15.4%) Pseudomonas aeruginosa, and 11 (10.6%) E. coli while the other Gram-nega-tive MBL producing bacteria were few in number. The blaIPM gene was detected in 1 (1.3%) case of Acinetobacter baumannii and 1 (1.3%) case of Stenotrophomonas maltophilia. These strains were found to be multi-drug resistant with high MICs (≥ 8 to ≥ 256 µg/mL) against the majority of the drugs.

The emergence of the blaIPM gene is a matter of serious concern as it left us with limited treatment options of minocycline, tigecycline, and levofloxacin. The horizontal transfer of blaIPM gene in other Gram-negative isolates can lead the epidemics of multidrug resistance.